1. Field of the Invention
The present invention relates to an ink-jet recording method for generating clear images by using a recording apparatus including an ink-jet recording head having a plurality of orifices.
2. Description of the Related Art
In an ink-jet recording method for recording images on a recording medium such as a recording sheet by moving (main-scanning) an ink-jet recording head with a plurality of orifices relative to the recording medium, a so-called multi-droplet method has been conventionally used for representing a tone wedge of a recording image. In the multi-droplet method, a plurality of ink droplets are landed or deposited on substantially the same position on a recording medium, and a pixel having an area according to the number of the plurality of ink droplets is formed. In this case, the tone wedge of the recording image is represented by forming a pixel having an area according to the image data.
When the multi-droplet method is used for recording images, all the images are generally recorded in such a way that the recording head is moved (main-scanning) relative to a recording medium for recording a part of the images, and then the recording head is moved (sub-scanning) perpendicularly to the direction of main-scanning and the main-scanning is carried out for recording another part of the images. That is, the main-scanning and the sub-scanning are carried out by turns so that all the images are recorded on the recording medium. In the conventional ink-jet recording method, the above feed distance of the recording head in the sub-scanning direction is a distance between two orifices provided on the recording head or a distance determined by the product of an orifice pitch and the number of orifices.
In the conventional ink-jet recording method, since, however, the feed distance in the sub-scanning direction is determined as the above described distance value, a portion not recorded of a so-called "white stripe (banding)" is generated in a recording image when an actual feed distance is greater than the predetermined distance value. On the other hand, when the actual feed distance is smaller than the predetermined value, there is a problem that ink droplets, the number of which is about twice as large as the number of ink droplets forming a predetermined pixel, land on the same position and a portion of a so-called "black stripe (banding)" of an extremely high image density is generated. In order to solve these problems, the feed distance in the sub-scanning direction may be precisely controlled so as to be always constant under any condition. However, this causes a very expensive manufacturing cost of the ink-jet recording apparatus.
Moreover, in the ink-jet recording head, volume of one ink droplet, which is discharged from one orifice in a vicinity of an edge portion of orifices disposed in a row, may fluctuate due to a temperature distribution in the use of the ink-jet recording head or unevenness of products caused by manufacturing and machining processes. As a result, in an image area, recorded in one main-scanning, unevenness of the image density may occur between portions recorded by the orifices in the vicinity of the edge portions of the recording head and portions recorded by other orifices.
As described above, in the conventional ink-jet recording method, the image quality in a vicinity of a boundary between an image area recorded in main-scanning and an image area recorded in next main-scanning may deteriorate for the above reasons.